fix(rustup): update io import, Writer::write

Make it build with the latest rust-nightly (2015-01-27)

Renamed io import to old_io.
Renamed Writer::write to Writer::write_all

src/server/response.rs

@@ -2,7 +2,7 @@
 //!
 //! These are responses sent by a `hyper::Server` to clients, after
 //! receiving a request.
-use std::io::IoResult;
+use std::old_io::IoResult;
 
 use time::now_utc;
 
@@ -141,9 +141,9 @@ impl<'a> Response<'a, Streaming> {
 }
 
 impl<'a> Writer for Response<'a, Streaming> {
-    fn write(&mut self, msg: &[u8]) -> IoResult<()> {
+    fn write_all(&mut self, msg: &[u8]) -> IoResult<()> {
         debug!("write {:?} bytes", msg.len());
-        self.body.write(msg)
+        self.body.write_all(msg)
     }
 
     fn flush(&mut self) -> IoResult<()> {